This invention concerns a device and a method for air filtration. The invention also concerns a system for air filtration.
Impurities in indoor air may be categorised in two categories, firstly particles emanating from humans, activities, textiles, papers and other surfaces and the very small, submicroscopic particles coming from outdoor air such as from combustion engines, mainly diesel engines. Further, pollen, street dust etc. The second category is comprised of gases, of which CO2 generally is most important, since too high CO2 level in the indoor air results in deteriorated performance for humans being inside the premises.
Up till now it has been suggested to reduce the influence of these kinds of impurities by change of air and central air cleaning in the building, which can be more or less controlled as a response to measured CO2 level and possibly the counted number of particles in the indoor air. Conventionally xe2x80x9cbetter air qualityxe2x80x9d has been equated with a greater intake of outdoor air. This has, however, proved to be an inadequate analysis, since in principle the higher the air flow the less effective the filtration is in central filter banks, resulting in that the conventional technology for solving one problem (high CO2 level) instead creates a risk of creating another: supply of large amounts of unwanted particles to the rooms.
Separate particle filters to be employed in rooms are previously well known. These filters, however, do not provide an acceptable air quality with respect to total impurity level in the air.
It is an aim of this invention to provide a device and a method whereby the problems of the prior art are eliminated or at least essentially reduced. It is also an aim to provide an efficient solution to the task of tailored cleaning of indoor air with respect to the activity profile.
This aim is obtained according to the invention in a device and a method as above.
This aim is obtained according to the invention in a device and a method as above through the features of the characterising portions of claims 1 and 12, respectively.
Hereby the air cleaning may be adapted to the prevailing air conditions in the premises in question. For example, a filter for coarse particles may be coupled in parallel and be combined with a filter for fine particles, or a particle filter with a gas filter, whereby the cleaning may be tailored for the respective environment and effectively take care of different kinds of impurities. By mixing the differently cleaned air fractions, a dilution effect is achieved in the supplied air, resulting in advantageously reduced levels in cleaned and supplied air. Through the construction of the device, simplicity with respect to production, use, service and installation is achieved as well as possibility of highly effective use of filters, since the walls of the device almost totally may be comprised of filters if desired or needed.
By the mixing taking place in a suction chamber, high efficiency and simplified construction of the device is achieved. Placing the fan in the suction chamber itself is an advantageous room saving aspect.
Through the invention, xe2x80x9cnormalxe2x80x9d ventilation may be replaced or supplemented. The impurity particle level in the room in question and of the ventilation system may be reduced. Further, the energy consumption may be reduced at the same time as air quality may be enhanced.
In a further advantageous aspect of the invention, air from the outside is supplied from a distance to the device. This way for example outside air may be supplied to a highly effective particle filter which is placed in the device, whereby good ventilation is guaranteed at the same time as is harmful particle shaped impurities in the outside air are eliminated. This may be carried out at the same time as another part of the device cleans the air in the room in a re-circulating manner. This mix hereby results in clean oxygen rich air being mixed with clean warm indoor air.
By adjusting the exhaust as well as the blower effect, the ventilation in the premises in question may be controlled for achieving the desired effect i,e., the device according to the invention may be made adjustable for the different principles of directing air through ventilation, namely for displacement as well as mixing ventilation through the possibility of controlling the supplied air with respect to speed and distribution.
Further advantages will become clear from the following description of embodiments.